wave1957

I have just driven my on-again/off-again '70 Impala with a Magnacharger-blown stock LQ9, and something seems funny with the engine cooling:
Engine idling a few minutes, the electric fan comes on at 200 degrees (according to brand new Equus electric gauge).
Temp still rises to 240.
Drive around the neighborhood (20 minutes), fan on all the time, temp between 230 and 240; a couple of WOT blocks, the rest at the speed limit, 30/40mph.
Back home, fan still on, heater and top rad hoses are really hot to the touch, but coolant in recovery tank is cool, pretty much room temperature...
I have installed my gauge sensor a few days ago in the rear location of the left side cylinder head, and I wonder if I created an air bubble in the system, which would prevent the coolant from circulating? How do I get rid of the bubble?
I did not notice this problem last time I drove the car, about 6 months ago and that gauge sensor is the only difference on the car...
Thanks

rotor vs. piston

iTrader: (3)

Bleed the system and drive at highway speeds (< 50mph) and see how it cools, it should read right around whatever temp thermostat you have.

If it's still running too hot it could be a stuck open thermostat.

wave1957

How do you bleed the system?
I have a stock thermostat, what temp should it be?

PowerAdder

When the thermostat opens hot coolant flows threw the top hose and down the radiator into the thermostat, into the engine block. there will be a notable change in temp between these 2 hoses, the lower being cooler. On my swap I fill the engine and radiator with the top radiator hose disconected from the water pump. Funnel into the water pump neck, fill untill full. It will gurgle out and you may have to wait for the level to drop in the neck to finish topping it off. As the block fills up bubles get traped and slowly exit. then I fill the raidiator via the raidiator hose that was disconnected holding it higher than the engine. If the thermostat is open you will see the water level in the block rise while filling here and you may push more air out. When the block and or radiator hose is compleately full I put my hand over the hose end and quickly slide it on the water pump neck. I Havent had an issue with air ever when doing this. You could just remove your thermostat if you think its stuck closed. Put it in boiling water it should open. My car holds at 200 degrees on the stock thermostat.

Pop N Wood

iTrader: (1)

Another option is removing one of the steam vents on the front of the motor when filling. Cap it back off as soon as you get coolant flow out of the block.

Sometimes it just takes a couple of run-refill through the radiator cap cycles to get all the air out. Jacking up the front end so the radiator cap is the highest point helps too.

wildcamaro

iTrader: (15)

Jags that run sells an LS specific radiator splice with a coolant bleeder which is very handy, my 81 LS camaro ran at 230-235 then I bled it good now I run at 180 all day...

john 67

had same problem a few weeks ago . I ended up removing a heater hose ( quickly ) and pincing off and raising ( the heater side ) then I added a short piece of hose back onto the water pump side , filling and blowing gently . lots of air came out through rad.repeated a few times , then quickly put heater hose back on .JOHN

wave1957

Thanks for all the answers!
I remember now that I had to fill the cooling system as Poweradder described when I first swapped the engine. I sure was hoping to be able to avoid that hassle this time!
What are these steam vents at the front of the engine mentionned by Pop N Wood? Maybe that could be easier...
And I will buy one of those air bleeder from Jags that run, it will make life easier in the future, just in case... Can someone confirm it is this part I need?
http://www.jagsthatrun.com/Pages/Par...ightGlass.html

PowerAdder

The steam vents are small pipes that crossover between the heads, I dont think you need to mess with them personally. That vent from JTR would help bleed air but you still need to fill it as decribed if the raidiator is lower than the upper hose, like mine, then you cant rly fill it well otherwise.

Pop N Wood

iTrader: (1)

I'm telling you, popping those steam vents is very effective, much better and much easier than pulling a radiator hose. They vent the top of the motor so when you get water out of them you are guaranteed to have filled the block to the top. The JTR vent won't do that directly. The water pump outlets are slightly lower than the stem vents. The vents are O ringed so you don't have to worry about a gasket breaking down.

I pop them open whenever I drain the radiator. It takes 30 seconds to do and allows the radiator to drain in half the time.

kwhizz

This is the whole purpose of the steam vents.......

wave1957

My rad cap is higher than the top rad hose connection on the block, may even be higher than the steam vents (stock '70 Impala rad).
So, Pop N Wood, using your method, opening the steam vents, do I understand correctly that I can simply fill the whole cooling system through the rad cap, until coolant comes out of the steam vents opening, then?
Undoing this pipe across the head seems easier than popping a hose indeed... I am just looking for the simple and easy way... Cleaner would be good too!
Thanks

gagliano7

Air gets trapped in the heads when you fill it up. pull hose off of steam vent while your filling. I always fill radiator up run car with cap off and wait for thermostat to open and add as needed until full. i never put the cap on until it is full after thermostat opens. This method always works for me.

ls1nova71

iTrader: (4)

If your steam hose is hooked to the radiator and is higher than the heads, then taking them off isn't really going to do anything since the air will go out the hose. Am I missing something?

Tim94gt

iTrader: (2)

+1.

I do the same, but I also jack the front end up off the ground. It seems to help the air pockets escape.

bczee

iTrader: (12)

on Pop's recomendation to pop the Steam vent (simple to do with a socket and extention). You don't have to do it at the port itself, if it is hard to get at. I just lossening the steam hose. Which is what I do to blead my system. And being (most of us) the TB is by passed, it is usually a simple task.

With my system, I have AN fitting.. so I just take a wrench and crack the fitting at the Radiator (which is where my steam hose goes to) and it is done..

BC

Pop N Wood

iTrader: (1)

That's what I do. Jack the car up to get the radiator cap higher than the motor, disconnect the vent, fill until coolant comes out of the vent, reconnect the vent and keep filling until the radiator is full. Only thing left to do is top the radiator back off after a heat cycle.

wave1957

Silly me!
I just remembered that I have the shop manual for that engine...
So, I followed their instructions and it seems to work fine!...
Fill the surge tank, run the engine until warm, turn it off, hear the big suction noise when the engine empties the surge tank, redo as needed, easy!
Thanks for all the answers anyway, it is always good to learn how things work.
Oh, by the way, my engine was also low about 1 gallon of coolant, that was a big air pocket!!!